Ten years after Bulgaria last appeared on the international capital market, the country made a successful comeback, but the biggest test is yet to come, according to analysts.

Bulgaria could have achieved an even better interest rate, but deliberately underestimated its prospects to please investors and lure them to subsequent issues, according to sources, cited by the local media.

Bulgaria tapped last week international markets to raise funds to repay the first tranche of about EUR 835 M (USD 1.07 B) in 11-year eurobonds maturing on January 15, 2013. The next tranche however is due in 2015 and Sofia may be forced to go to the markets again.

"That's why it is important that foreign investors are happy now, so that subsequent issues are welcome. This is an investment in Bulgaria's positive image," an unnamed investment banker told Capital daily.

A week ahead of the Eurobond issue, Bulgaria's finance minister Simeon Djankov and central bank deputy governor Kalin Hristov launched a series of investor meetings across Europe, including some of the major players on the debt market.

A quarter of the bonds were purchased by British financial institutions, followed by those from Germany - 17%, according to data by the finance ministry.

Nine percent were acquired by Asian investors. Almost fifty percent of the bonds in the new issue went into the hands of investment funds, while 6% - at central banks.

Interestingly, the bond issue will mature in the summer of 2017, when the country will hold general parliamentary elections. But experts say this is just a coincidence, not a deliberately sought result.